In recent years, the share of renewable energy in Germany’s electricity supply has risen rapidly. It already stands at over 20 per cent, with around half coming from variable sources such as wind power and photovoltaics. With the long-term goal of achieving an almost entirely renewable energy supply by 2050, the electricity system faces a profound transformation. Against this backdrop, the TAB report examines how base load supply can continue to be ensured under these conditions. This question can only be answered systemically, i.e. by taking into account all levels of the electricity supply chain – from generation through transmission and distribution to consumption. This brings into focus the overarching challenge of how a secure supply can be organised as a whole. It is clear that, in future, the electricity system will need to respond much more flexibly to varying feed-in and demand situations. Opportunities to increase flexibility exist in various areas: through more capable grids, a more flexible design and operation of the conventional power plant fleet, a stronger focus on demand in renewable electricity production, load management measures, and the expansion of storage facilities. For all these areas of action, the TAB report identifies options for how government and energy policy stakeholders can contribute to the success of the fundamental restructuring of the electricity supply by establishing appropriate framework conditions. The TAB report examines the question of how the base load in the electricity supply can continue to be secured under these conditions. This question can only be addressed from a systemic perspective that encompasses all levels: from generation through transmission and distribution to the consumption of electricity. Consequently, the scope of the question broadens to include how a secure supply can be organised as a whole. It is evident that the electricity system must be able to respond much more flexibly than before to varying feed-in and demand situations.